Olefin thermoplastic elastomers have been widely used, particularly as substitutes for vulcanized rubbers, and more particularly in the field of molded products. These cross-linked olefin thermoplastic elastomers possess exceptional properties, including tensile strength, elongation at break, elastomeric properties, and heat resistance.
Historically, many of the elastomers of the type identified above, have been constructed of polymers made from a Ziegler-Natta catalyzed reaction. However, as described in U.S. Pat. No. 5,198,401, herein incorporated by reference, and International Application No. W097/11115, also herein incorporated by reference, the polymerization of olefins, diolefins and acetylenically unsaturated monomers to homopolymers and copolymers in the presence of an ionic metallocene catalyst is now producing unique materials. For example, the polypropylene polymers obtained via the metallocene catalysis process are generally at least substantially isotactic and often fully isotactic. As an additional example of a unique compound obtained via metallocene catalysis, low ethylene content EPR's are being produced. Specifically, the reactions are performed in the presence of a metallocene catalyst of the general formula EQU Cp.sub.m MR.sub.n X.sub.q
wherein Cp is a cyclopentadienyl ring or a derivative thereof; M is a Group IV, V or VI transition metal; R is a hydrocarbyl group or hydrocarboxyl group having from 1 to 20 carbon atoms; X is a halogen and, m equals 1 to 3; n equals 0 to 3; Q equals 0 to 3, and the sum of m+n+q is equal to the oxidation strength of the transition metal. Further examples of metallocenes catalysts and processes are provided for in U.S. Pat. Nos. 4,530,914; 4,871,705; 4,937,299; 5,124,418; 5,017,714; 5,120,867; 5,278,119; 5,304,614; 5,324,800; 5,347,025; 5,350,723; 5,391,790; and 5,391,789, each of which is herein incorporated by reference.